For several years, the only design tool I used was Sketch. I used it for sitemaps, user flows, wireframes, and visual design. That's changed. A few months back I stumbled across Whimsical, and immediately fell in love with how simple and quick it was to create sitemaps and user flows. It's my new favorite tool to quickly explore ideas in the early stages of a project. Recently, they expanding their service to offer wireframes, mind maps, and sticky notes, along with team collaboration. I've been using sticky notes like a kanban board and it's just what I need to manage my personal workload. They also have some great articles ranging from "How We Designed Whimsical for Speed" to "10 Reflections from Founding a SaaS Startup".